Pulling cord winding apparatus for window shades

[0001] The present invention relates to a pulling cord winding apparatus for window shades that includes a push rod and a brake member that are movable and an arched pressing plate to prevent pulling cords from entangling or forming knobs during winding, and also has cord pressing members and cord clamping members to prevent two elastic coils from slipping at the maximum force during cords winding to extend and retract a window shade.

[0002] A conventional window shade generally is lifted or lowered through a rope. The rope usually is exposed outside and could cause a hazardous condition by tangling or strangling children playing nearby. Hence for safety reason the rope of the window shade is generally collected in a winding device located on the bottom rail of the window shade without exposing to prevent risks.

[0003] There are many types of pulling cord winding devices for window shades on the market. FIG. 1 illustrates one of the examples (namely U.S. Pat. No. 6,675,861 B2). It has a pulling cord winding device A installed on a front end of a bottom rail B1. The device includes a cord braking board A1 which has an upper pressing member A10 and a lower pressing member A11 which is coupled with a collar A12 to clamp a pulling cord C. When a window shade B is extended or retracted, the upper pressing member A10 is pushed downwards by a spring A13 to compress the pulling cord C. The compression surface A101 of the upper pressing member A10 and an opening A120 of the collar A12 form a V-shape shearing force (referring to FIG. 2A). The pulling cord C tends to be severed by the shearing force. When the lower pressing member A11 is moved upwards, the compression surface A111 of the lower pressing member A11 and a bore A100 of the cord braking board A1 form an inverted V-shape shearing force. This also tends to sever the pulling cord C (referring to FIG. 2B). Hence the pulling cord C is difficult to be anchored on a desired location. The aforesaid pulling cord winding device A not only is troublesome during operation, but also cannot anchor the window shade on a desired location during extension and retraction. Moreover, the pulling cord winding device A consists of many elements, and is too bulky. A bigger bottom rail B1 is needed to hold the pulling cord winding device A. In short, the entire device takes too much space and is too costly. The enlarged bottom rail B1 also becomes too heavy. And the spring A13 installed inside the pulling cord winding device A has to withstand a greater force. This shortens the service life of the device.

[0004] In view of the aforesaid disadvantages occurred to the conventional winding devices that cannot be anchored on a desired location during extension and retraction, and are bulky and costly, the primary object of the present invention is to provide a pulling cord winding apparatus for window shades that is lighter and has a smaller thickness to reduce the force exerted on the spring in the pulling cord winding apparatus. The invention is compact and may be easily installed on the bottom rail of the window shade.

[0005] The pulling cord winding apparatus for window shades of the invention includes an upper cap and a lower seat that are coupled together, two elastic take-up reels mounted on holding struts located in a center housing compartment formed on the lower seat, an elastic coil housed in each elastic take-up reel that has two ends latched thereon, a brake member coupled on a post located on one side of the housing compartment of the lower seat, and a push rod pressing the brake member. The push rod may be pushed to move the brake member to enable the elastic coils to be retracted or released thereby to extend or retract the window shade.

[0006] Another object of the invention is to form a latch slot on the anchor strut and a retaining member on an inner perimeter of the elastic take-up reel that has a latch trough to allow the two ends of the elastic coil to wedge in the elastic take-up reel.

[0007] Yet another object of the invention is to provide arched pressing plates on two sides of the brake member that have cord pressing members extended outwards. The cord pressing members have second teeth to engage with first teeth of cord clamping members located on two outer sides of the housing compartment. Hence when the push rod is pushed to move the brake member, the brake member escapes to enable the two elastic take-up reels to rotate and brake, the two elastic coils are retracted or released to enable the window shade to be extended, retracted and anchored on a desired location.

[0008] Still another object of the invention is to manage the pulling cords through the arched pressing plates, cord pressing members, and cord clamping members so that the pulling cords are retracted in a tidy manner without entangling or forming knobs, and the two elastic coils can retract the pulling cords without slipping at the maximum force.

[0009] Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood tat the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

[0020] Please refer to FIGS. 3 and 4 for the basic structure of the pulling cord winding apparatus according to the present invention. The pulling cord winding apparatus 1 is installed on the bottom end of a bottom rail 20 of a window shade 2 to wind and house pulling cords 21 and 22 on two sides of the window shade 2. The pulling cord winding apparatus 1 includes an upper cap 3 and a lower seat 4 that are coupled together, two elastic take-up reels 5 corresponding to two holding struts 41 and 42 located in a center housing compartment 40 of the lower seat 4, two elastic coils 6 having two latch ends 60 and 61 housed and latched in the elastic take-up reels 5, a brake member 7 coupled on a post 43 located on one side of the housing compartment 40, and a push rod 8 to push the brake member 7. The brake member 7 may be moved and escape to enable the two elastic take-up reels 5 to rotate and perform brake function. Thus the two elastic coils 6 are retracted or released to extend or retract the window shade 2.

[0021] The upper cap 3 is an elongate member with a recess 30 in the center of a front end, and sunk holes 31 and 32 on two sides and one side of the center, and a contact side 33 which has a wedge flange 34 on a front end and a rear end. The wedge flange 34 on the front end has a concave notch 340 in the center.

[0022] The lower seat 4 is formed in a shape mating the upper cap 3, and has the center housing compartment 40, and the two holding struts 41 and 42 on two sides that have respectively latch slots 410 and 420. The post 43 is located on one side in the center between the two holding struts 41 and 42, and has a screw hole 430 corresponding to the sunk hole 32. On the outer side of the two holding struts 41 and 42, there are two arched retaining flanges 44 and 45. In the center of the arched retaining flanges 44 and 45, there is a cord clamping member 440 and 450 that corresponds to each other, and has first teeth 441 and 451 on one side thereof. The lower seat 4 further has fastening struts 46, and each has a screw hole 460 corresponding to the sunk hole 31. Between two fastening struts 46, there is a strut 47 to couple with an axle hole 480 of a guide reel 48. The lower seat 4 also has a concave notch 49 and a recess 491 mating the concave notch 340 and wedge flange 34 of the upper cap 3, and two apertures 492 on two sides to allow the pulling cords 21 and 22 to pass through to extend and retract the window shade 2.

[0023] The two elastic take-up reels 5 have respectively a housing space 50, an opening 500 in the center of the bottom to couple with the holding struts 41 and 42. On the inner perimeter of the housing space 50, there is a jutting retaining member 51 which has a latch trough 510. Two elastic take-up reels 5 further have respectively flanges 52 and 53 extended from two sides to form a winding zone 530 in the middle to wind the pulling cords 21 and 22.

[0024] The two latch ends 60 and 61 of the two elastic coils 6 are latched respectively on latch slots 410 and 420 of the holding struts 41 and 42, and the latch trough 510 of the retaining member 51 of the elastic take-up reels 5.

[0025] The brake element 7 has two cord pressing plates 70 extended outwards from two sides that have a cord pressing member 700. The cord pressing member 700 has second teeth 701 on one side that are engageable with the first teeth 441 and 451 of the cord clamping members 440 and 450. The cord pressing member 700 further has a cavity 702 on another side to hold a spring 703. The brake member 7 has a jutting member 71 on the front side that has a housing cavity 710, and a slot 72 in the center to couple with the post 43.

[0026] The push rod 8 has a depressing head 80 on one end and other end to insert into the housing cavity 710 of the brake member 7.

[0027] For assembly (referring to FIG. 5), wind the pulling cords 21 and 22 on the winding zone 530 of the two elastic take-up reels 5; couple the opening 500 with the holding struts 41 and 42 of the lower seat 4 with the latch ends 60 and 61 of the elastic coils 6 latched respectively in the latch slots 410 and 420 of the struts 41 and 42, and the latch trough 510 of the retaining member 51; press the arched pressing plates 70 of the brake member 7 on the winding zone 530 of the two elastic take-up reels 5 to engage the second teeth 701 of the cord pressing member 700 with the first teeth 441 and 451 of the two cord clamping members 440 and 450 (referring to FIGS. 6A and 6B); insert the push rod 8 into the housing cavity 710 of the brake member 7, and couple the slot 72 of the brake member 7 with the post 43; place the push rod 8 in the concave notch 49 of the lower seat 4; couple the wedge flange 34 of the upper cap 3 with the corresponding recess 491 of the lower seat 4; screw fastening elements 310 through the sunk holes 31 and 32 into the corresponding screw holes 460 of the fastening struts 46, and the screw hole 430 of the post 43 to finish the assembly of the pulling cord winding apparatus 1. Thread the two pulling cords 21 and 22 from two sides of the window shade 2 through the apertures 492 on two sides of the lower seat 4 and wind the pulling cords on the winding zone 530. The pulling cord winding apparatus 1 thus formed has a smaller thickness and is lighter. It can reduce the force exerting on the spring 703 inside the winding apparatus. The pulling cord winding apparatus 1 is compact and may be installed easily on the bottom end of the bottom rail 20 of the window shade 2.

[0028] Referring to FIGS. 5, 6A and 6B, when in use, push the depressing head 80 of the push rod 8 to move the brake member 7 and compress the springs 703 on the two cord pressing members 700, the arched pressing plates 70 are moved away from the pulling cords 21 and 22 wound on the winding zone 530 (or returned to the compression condition). The brake member 7 escapes, and the two elastic take-up reels 5 can rotate and brake. Hence through the arched pressing plate 70, the pulling cords may be retracted smoothly without entangling or forming knobs. By means of the cord pressing members 700 and the cord clamping members 440 and 450, the pulling cords 21 and 22 do not slip when the two elastic coils 6 release the maximum forces, and the window shade 2 may be lifted and retracted or lowered and extended immediately. When there is a desired to stop the window shade 2 during extension or retraction, release the depressing head 80 of the push rod 8, the window shade 2 may be anchored at a selected elevation.

[0029] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.